Return-path: Received: from xc.sipsolutions.net ([83.246.72.84]:36877 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751435AbZCPHPi (ORCPT ); Mon, 16 Mar 2009 03:15:38 -0400 Subject: Re: [PATCH] mac80211: Tear down aggregation sessions for suspend/resume From: Johannes Berg To: Sujith Cc: Bob Copeland , "linville@tuxdriver.com" , "linux-wireless@vger.kernel.org" , Jouni.Malinen@Atheros.com In-Reply-To: <18877.56125.181203.703218@gargle.gargle.HOWL> References: <18876.41851.397740.847705@gargle.gargle.HOWL> <1237140134.24621.0.camel@johannes.local> <18877.56125.181203.703218@gargle.gargle.HOWL> Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-lIHMr14m2PMwzKnpUd/u" Date: Mon, 16 Mar 2009 08:15:28 +0100 Message-Id: <1237187728.27769.2.camel@johannes.local> (sfid-20090316_081542_593055_2EA0AE7B) Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: --=-lIHMr14m2PMwzKnpUd/u Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Mon, 2009-03-16 at 10:23 +0530, Sujith wrote: > > I think the deadlock went away, not sure what fixed it but I guess > > the HT rework. I tested it a couple of weeks ago on ath5k and Luis > > did on ath9k so I say let's go ahead and apply the patch... in the > > meantime I'll try again on ath5k just to be sure. Ok. > There is a window for a race. Something like this: >=20 > From mac80211: >=20 > __ieee80211_suspend() > tear_down_BA_sessions(TX, RX) > ampdu_action(STOP) > remove_vifs() >=20 > At this point, the driver executes its remove_interface routine. > While we are doing this, a TX completion interrupt could be raised, > (HW hasn't been stopped yet) and nothing stops the driver from calling > ieee80211_start_tx_ba_session(). >=20 > So the question is: should mac80211 deny ADDBA requests in this case ? Interesting observation. We probably should indeed reject that, and also if the peer asks for sending aggregation again right away like some Broadcom APs will. johannes --=-lIHMr14m2PMwzKnpUd/u Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Comment: Johannes Berg (powerbook) iQIcBAABAgAGBQJJvfyNAAoJEKVg1VMiehFY5P4P/Rnk5hlaZYAfHtbjNoDxJwuv CwcS2QqmVfMGgGgbjTOtlEbUcdn3DlRXmP5BNMPWSFQ//FlHPx8mGad5d/kd6RuB bXHa5ECprokE7eYd1kcz6RCGhk/8uPMf4F8s3N3/zmB0pPTy6hyAfkJ7BoaoZfCH sIQGAqqa3zORK5KM9dnXzdAuaTYB5492PnJL9l+qtYs/RWuHHLoksb/1rOxDEqW/ D2BAwd7Xk1tIfHZdY+TMm9zYk89ZtL0sjQGIkuy1kbG0cLYo/roiNRj2t7cJxO49 /vJfCv/Cvwtq8pUtkRVhAMSLMSvTHEy6gz6lvglTbuHCZ1EmAIWxGUZwyFNHi+2R IAjQRH2mMEedI60Grn5vPCTTLF6Tm7DrXi6JYLznGLWK6HJfjmFiAv9qj0Yhr5qH VdiJqryff5jIsszEGpNyBC2f6OvLgkBM7w4qypnUpUwZ8D1+CYx+I0H5yAL7rl/5 pA/s/hyRZnR+m7FyhU9LXbzGYelwk06028oeJ88ZjqfJgZvoSbS0qKkRpfmydqWb PC2XdCUPctCLlQ1x025fF2rQU0Omfbrcp342/dQUEX8BDFQKFzd2MZVfb3KASr+l YIaFaVN3nYDi/ZX3C/RYkAj1abLIRj63SoQsaszw6sSILJ0F54zr5NYJsH1mZUfN ryz4wsNpxWK1yOn0sy6X =p6V+ -----END PGP SIGNATURE----- --=-lIHMr14m2PMwzKnpUd/u--